Formation of metal strip under controlled pressures



May 26, 1953 J. B. BRENNAN FORMATION OF METAL STRIP UNDER CONTROLLED PRESSURES Filed Aug. 12, 1948 will!!! If! lwflvv 3nventor Joseph Brennan WM 5" Gttoruegs Patented May 26, 1953 FORMATION OF DIETAL STRIP UNDER CONTROLLED PRESSURES' Joseph B. Brennan, Cleveland, Ohio Application August 12, 1948, Serial No. 43,881

8 Claims.

This invention relates to the formation of continuous or elongate, metal strips, especially to the formation of such metal strips under controlled pressures, usually appreciably below atmospheric.

Metallic strips made in accordance with the teachings of the invention are particularly suitable for use in the manufacture of electric condensers although they may be used in any desired manner.

In the formation of metal strips of the above class, one method of forming such strips is to spray metal continuously onto a moving base strip and solidify such metal onto the base strip so as to form a continuous metal strip from the deposited metal. Formation of uniform metal strips that have desirable electrical properties is diflicult since the sprayed metal tends to form strips which are not of the same gauge throughout. Furthermore, sometimes it is difficult to obtain the degree of porosity or density desired in such metal strips. Also, excessive oxidation is frequently present and the degree of fineness of spray is ordinarily dimcult to regulate, in atmospheric spraying operations.

The general object of the present invention is to provide a novel, effective method of producing elongate metal strips or metal layers of uniform composition and electrical properties.

Another object of the invention is to deposit sprayed metal particles onto a base strip with the spraying and depositing action occurring under subatmospheric pressures.

A further object of the invention is to deposit sprayed metal particles uniformly in a completely controlled atmosphere.

A further object of the invention is to control the temperatures of sprayed metal particles and to control the temperature of a base strip onto which the metal particles deposit.

Another object of the invention is to utilize increased pressure differentials in spraying molten metal. I

A further object of the invention is to provide a metal strip made from spray deposited metal particles which is free from entrapped gases.

The foregoing and other objects and advantages of the invention will become apparent as the specification proceeds.

Attention is directed to the accompanying drawing wherein:

Fig. 1 discloses a vertical section of one form of apparatus for practicing the invention; and

Fig. 2 is a fragmentary section taken on line 2--2 of Fig. 1.

The present invention is a continuation in part of my copending application entitled Method of and Apparatus for Spraying Metal, Serial No. 548,023, filed August 4, 1944, and now abandoned.

The specific apparatus disclosed herein is de-.

2 scribed in more detail in a copending application Serial No. 1,926, filed January 13, 1948, by Robert M. Brennan, wherein such apparatus and its use is claimed.

The structure shown in the drawing includes an enclosed chamber I0 in which is positioned a metal storage pan or crucible II, which has an extension spout I2 provided thereon. An inverted container I3 is positioned over a portion of the metal storage pan I I and is supported thereby. The inverted container I3 is adapted to receive a supply of molten metal I4 therein and retain same at a difierent level from metal in the extension spout I2. This action is effected by means of an outlet I5 that is formed in the container I3 adjacent the extension spout I2 of the pan II. Any conventional means are associated with the outlet I5 so as to regulate the fiow of the molten metal therethrough. In this instance, a float type of valve is provided for maintaining the metal I4 at a predetermined level in the spout I2 and such device includes a gate valve I6 that has 2. lug I'I extending outwardly therefrom. The gate valve I6 is positioned within the container I3 and seals the outlet I5 when the valve is seated on the inner surface of the container I3 adjacent the outlet I5. A float I8 is provided and is carried on the metal I4 in the extension spout I2. This float I8 connects through a lever arm I9 to the lug H on the gate valve I B. A pin 2I extends through the lever arm I9 and pivotally secures it to an extended portion of the container I 3. Thus as the level of the molten metal in the extension spout I2 falls below a predetermined value, the float I3 will cause the valve IE to be opened slightly and metal from the supply chamber will flow into the spout to maintain the metal level therein substantially constant even though metal may be intermittently or continuously withdrawn therefrom.

The container I3 may be supplied with a storage ladle 22 which is positioned within the container and is controlled from the outside of the container by means of a control arm 23. The control arm 23 may be extended to a point beyond the confines of the chamber I0, if desired, so that, in all events, metal can be placed inside of the inverted container I3 through a trap feed tube 24 provided for the container and such molten metal may be stored in the ladle 22 and added intermittently to the pool of metal retained in the container I3.

The foregoing apparatus will maintain a constant or uniform pressure head of molten metal in the extension spout I2 and any type of spray device may be associated with or connected to the extension spout I2 so as to be supplied with .a uniform pressure source of molten metal. In this instance a nozzle 25 is shown secured to the .lower surface of the extension spout I2. This nozzle 25 has a plurality of gas passageways 26 formed in the end portion thereof and a tube 2'! may connect. thereto ,for supplying 'gasxto the passageways ilt which-discharge the gas immediately adjacent and converging upon the bore 26 of the nozzle 25 at the end of the nozzle. In"

some instances the tube 2! Willnot be used.

In order to control the temperature oflthe' mol' ten metal prior to its ejection from the nozzle 25, an induction heating coil M maywbeposie tioned around the inverted container.v l3 whilea.v

second induction heating coil3l"'may"be" positioned around the nozzle 25. ing high frequency electrical energy to the coils 2H and. 3 l..any...desired temperature-or fluidityof. the materialgtherewithin maybe set upgby vari ation. of the. amount of heating. current provided to such'coils'. Of course, the pan .ll, container 7 l3 and nozzleZE areformed from .a.conventional material, usually. refractory, so as. to remain.un-. affected (by any heating. energy supplied to l the metallic material ML Inicase the metallkshould overflow fromtheextension. spout 12 for anyreason, it. willi pass overalip- 32 formed onlthe spoutlz 'and be caughtlina receptacle 33 'from which a pump as will. force the material .back into the container it through a conduit 35..

1A salient feature of the present invention is that. the sprayingor.deposition. of the molten metal. i4 occurs under a vacuum. Hence avacuumpump13'6 connects to a lowerIsection W of the chamber. l andiserveslto set upja desired vaeuumwitliinsuchchamber section. Thus the metallic material .inthe extension spout I2 issubjected. to. a desired pressure whereas .the depositionof. Such metal also occurs under a. desired sub-atmospheric pressure. Production of a.-.continuous.metal-strip from the sprayed metal particles. is facilitated by. means of a .backing stripdlthatis led bythe nozzle 25 so as to receive all. metal particles ejected therefrom; The backing .-,strip ,3.1. isishown as .being originally stored on airolll38. and as passing ,to. a final storageroll-tflh i The. backing stripi 3T may be made from, any desiredmaterial and one..very. satisfactory substance. is a thin," soft, porous strip of paperiwhereaslmatt'ed fibers also might be used in some instances, and other desired backing'materials-may be used. In some instances wherein *aporous..metal strip with no backing material carried thereby is. desired, the backing strip 31 shouldbe madeirom-a smooth, highly polished meta-l,- suchas stainless steel, and'sucha belt is used in the drawings forming a parthereof; In such instance, the. deposited metal particles would coalesce. and combine as. they are sprayed Qr-depositedso as to: produce a continuous uniform. metal strip which'would be onbut not intimately bonded to the backing strip'31.' After production of the-sprayed metal strip, it could be separated fro-mthe backing strip ,31. at any convenient timei-tosprovide. a metal strip free from any objectionable.backing. material. In.. some instances-uwhere. aipapersor fibrous .backing is used;v it. is possible to ignite thebacking strip after it has been usedito. .form a metal. strip thereon and such/combustion .will' eff ctivelyremove all or-substantially. all of. the original backing materiaL.

Itmay be. desirable to-t control the temperature of themolten metal M as it moves from the nozzle. 25..and diffuses out for deposit onto the backingstrip 31. Hence a control funnel 4i is,positionedadiacent the nozzle 25 'for"receiv- Hence byfsupply-v on the backing strip 31.

ing the sprayed metal particles and another high frequency electrical heating coil 42 may be positioned'around the oontrol funne'l 41 for control of the temperature ofQ-th'e metak'particles as they move through the chamber II] for deposit Of course, the roll 39 is usuallydriven so as to move the backing strip 3lifpast'fzthefnozzle 25 at a desired rate to control depo sito-f metal onto such backing strip.

: In'Ysome-instances it may be desirable to vary or control the temperature of the backing strip 31*. I-Inceenywo-nvenient temperature control means'may be associated with the roll 38 or with a portion of the backing strip 31 as it leaves the 101138 soas. to heat oricool the backingsstrip-to a-de'sir'ed temperature. 4.

As best shown. in Fig.;2, a coolingishoe Hillis provided for associatio'nwiththe under surface of the backing strip 31. Thiscooling shoe N10 is particularly adapted to be used when-:the backingstrip 3l'is formed from metallic mate-. rial from which the depositedx'm'etal 'is toib'e thereafter separated in the form; ofJaporous metal .trip. The c-ooling'shoe' lfiu'ha's cooling fluid, usually water, supplied thereto througha tube- 61- and an exhaust tube or conduit I02 also connects to the cooling shoe for exhausting cool ing. fluid therefrom. It wilhbe noted'that'the upper surface of the cooling shoe 109 has. av-recess 1% formed therein inlwhichthei strip 31' is positioned. 7

As a speciali'eature' of the present invention; deposition of molten metal. along the edges'of the stripsiis prevented bymeans of endless bands; or other suitable means, indicated at tilt and E05 which are adapted-t6 overlie the edges ofthe strip 3? and move alongtherewith; These hands We and lfiii'may be positioned'ion rolls H13" and; if necessary, other guide rolls'may be provided to prevent the bandsfrom striking the guide'tube or funnel ll. ontth'e return. str'etchmovement of the bands. Preferably a scraperiillis' provided to scrape undesired metal 'depositingonto me bands M4 and its from conta'ctl'therewith: 'Ilie' rollfid isishown provided for receipt of a stainless. .steelbandlii'l thereon. In some. instances even though the stainlesssteelbandis not used, and-it. is desired .to heat orcoolthe deposition strip, the shoe Hi5} have =desired-l1eating or cooling fluid associated therewith.

Of course; any desired drive means= may be provided iortherolls-I86. Normally the. bands lu l-and m5 shouldbe driven at identically the.

same speed asthe-backing;strip 3'1:-

The drawing also shows that the backing strip 37- passes between :a pair of rolls-43 and after metal is deposited onto the backing strip- The rolls.- 63 and li i 'may bepositioned-at any desired pointadjacent the nozzle 25 to-receive the back ing strip after metal. has been deposited thereon. The rolls E3 and 34 are provided to compress or :compactand i coalesce metallic 1 particles on the *backingstrip: to prevent 'gas entrapment in the deposited metal, whichentrapmentsisavoided byfiuse ofa vacuuzni"atmosphere;-: Ordinarily the metal strip produced" by"-the metal particlesadepo'sited rthrough the nozzle 25. iWilIbe porous and. the. degree: Soil porosity can be. con trolled by variation of: the I degree 1 "of vacuum within the chamber If]. The .greaterthe vacumng. the sloweristhe coolingof the: deposited: particles and-the slower the cooling of1th'e1 deposited par: tiucl'e s, the less the porosity of the resultant metal s rlp.

The metal strip may be heated to the point of vaporization and attain a mirror-like, continuous, dense metal in the strip, which heating may occur at any desired time.

While any desired material may be sprayed in accordance with the invention, the method is primarily provided for the formation of metal strips from aluminum or magnesium. Aluminum strips are particularly suited for use in the production of electrodes for electric condensers.

By practice of the present invention, a uniform metal deposit action can be realized to produce a uniform size metal strip which has uniform electrical properties.

As previously pointed out herein, any kind of apparatus may be used in the practice of the invention and likewise any desired operable size of apparatus may be used. The base strip may be formed of any desired composition and it is even possible to use a polished cylinder for deposit of sprayed material thereon with. the strip produced being continuously removed from one portion of the cylinder while molten metal particles are continuously deposited on another portion of the moving cylinder which would be driven in a uniform manner.

Of course, only the end of the nozzle and the deposit means may be subjected to a vacuum if desired and any desired pressure, usually above atmospheric, may be set up in the chamber by any desired type of apparatus. It also is possible to set up a diiferent pressure in the container 13 than exists at other points within the chamber in. Even hydraulic pressures in excess of 2150 pounds per square inch in differential may be used in chamber It in relation to the spray section 10*, and no atomizing gas as shown entering at 21 is needed, only the pressure and heat on the molten metal being utilized to make a fog or mist thereof as such molten metal is being deposited. The action of the metal when sprayed, will be at least partly dependent upon the nozzle design and any desired nozzle construction may be used.

In depositing metal in accordance with the invention it will be realized that the metal may be atomized, or vaporized, when in the process of deposition since the release of the heated metal into the vacuum through the nozzle 25 may cause such action, and this action may result regardless of whether a carrier gas is provided for the hot metal or not. By the pressure on the hot metal, a directional spraying of same, whether leaving the nozzle as a liquid or gas, can easily be effected. The spray action will be controlled by the temperature of the sprayed metal, the degree of vacuum in the chamber 10 the pressure in the chamber (0, and the design of the spray nozzle.

Usually the deposited metal is received upon a moving base strip but the invention is not limited to such deposition action.

While one complete embodiment of the invention has been disclosed herein, it will be appreciated that modification of this particular embodiment of the invention may be resorted to without departing from the scope of the invention as defined by the appended claims.

Having thus described my invention, what I claim is:

1. That method of depositing metal comprising the steps of liquefying a metal, applying a constant pressure to the metal, and spraying the metal under pressure into a reduced pressure atmosphere to aid in vaporization and atomization of the sprayed metal while it is projected in a desired direction.

2. The method of producing an elongated metal strip comprising continuously depositing discrete molten metal particles from a uniform pressure head of molten metal onto a base member, and maintaining a partial vacuum on the molten metal particles during such deposition.

3. The method of producing an elongated metal stripcomprising continuously depositing discrete molten metal particles from a uniform pressure head of molten metal onto a base member, maintaining a partial vacuum on the molten metal particles during such deposition, and compacting the deposited metal while retaining it under a partial vacuum.

4. The method of spray depositing a layer of molten metal comprising maintaining a constant head on a body of molten metal, depositing the metal on a base by spray discharging it from the body of metal toward the base, and maintaining a partial vacuum on the discharged metal during such deposition.

5. The method of uniformly spraying molten metal to form a composite strip comprising the steps of maintaining a constant head on a body of molten metal and a constant level of the molten metal, and continuously depositing metal onto a base strip by spray discharging it from the body of metal toward the base strip.

6. The method of forming an elongated metal strip comprising the steps of maintaining a constant head on a body of molten metal, continuously depositing the metal onto a base by spray discharging it from the body of metal toward the base, and continuously removing the spraydeposited layer of metal from the base as an elongated strip.

7. The method of forming an elongated metal strip comprising the steps of maintaining a constant head on a body of molten metal, continuously depositing the metal onto a base by spray discharging it from the body of metal toward the base, continuously removing the spray-deposited layer of metal from the base as an elongated strip, and controlling the exposed width of the base to regulate the width of the spray-deposited strip.

8. The method of forming an elongated metal strip comprising the steps of maintaining a constant head on a body of molten metal, continuously depositing the metal onto a base by spray discharging it from the body of metal toward the base, and continuously moving the base at a constant lineal speed past the spray of the molten metal whereby to form thereon a spray deposited layer which is of uniform thickness longitudinally of the base.

JOSEPH B. BRENNAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,164,008 Moore Dec. 14, 1915 1,179,762 Schoop Apr. 18, 1916 1,299,988 Metzger Apr. 8, 1919 1,496,309 Girvin June 3, 1924 1,654,509 Claus Dec. 27, 1927 2,074,281 Sommer Mar. 16, 1937 2,159,297 Shover May 23, 1939 2,217,039 Beck Oct. 8, 1940 2,332,309 Drummond Oct. 19, 1943 2,382,065 Kappeler Aug. 14, 1945 2,402,269 Alexander et a1. June 18, 1946 2,423,051 Smith et al June '24, 1947 

